Active Noise Cancellation (ANC) is a critical feature in headphones that allows users to enjoy their audio content in a more isolated and immersive manner by reducing or eliminating external noises. This technology has gained widespread acceptance and popularity among users of headphones and earphones for its ability to reduce or eliminate external noises.
Today, ANC has become a standard feature in many premium and high-end headphones, and it has also been increasingly integrated into mid-range and even some budget-priced headphones. It has been widely adopted in various types of headphones, including over-ear, on-ear, and in-ear headphones, as well as in some earbuds and earphones.
How ANC Works
ANC headphones have built-in microphones that capture external noises from the surrounding environment. These microphones are strategically positioned on the ear cups and other parts of the headphones to capture a wide range of noises.
The captured external noises are then analyzed by the ANC circuitry system, which identifies the frequencies, amplitudes, and other characteristics of the external noises. Based on the analysis of the external noises, the ANC system generates sound waves that are opposite in phase to those noises. These opposite sound waves are also known as anti-noise or negative noise.
The system generates these anti-noise sound waves in real-time, taking into account the characteristics of the external noises and the desired audio content. The generated sound waves are then mixed with the audio content the user wants to listen to. This is achieved by combining the sound waves with the audio content at the headphone’s drivers, which are responsible for producing the sound that reaches the user’s ears.
ANC systems also have the ability to continuously adjust the anti-noise sound waves in real-time based on changes in the external noises or the user’s listening environment. This ensures that the ANC system adapts to varying noise conditions and maintains effective noise reduction performance.
Feedforward ANC vs Feedback ANC
Feedforward and feedback ANC are two different approaches used to cancel out external noises in headphones or earphones. Generally, both feedforward and feedback ANC can provide effective noise cancellation in headphones and earphones, but they use different concepts to capture and cancel out the noise.
Feedforward ANC
Feedforward ANC is a type of ANC system that uses external microphones to capture incoming noises from the environment. Ideally, external noises are captured by microphones placed outside the ear cup or earphone housing. These microphones pick up the incoming sounds from the environment, including noises such as traffic, airplane engines, or other ambient noises that the user wants to cancel out.
Advantages of feedforward ANC
- Feedforward ANC is particularly effective at canceling out high-frequency noise, such as airplane engine noise or traffic sounds, which are common in many listening environments.
- Feedforward ANC has low latency, which means that the cancellation of external noise happens quickly and in real time.
- Feedforward ANC doesn’t directly affect the audio signal being played, as it cancels out external noise before it reaches the ear. This means that the audio quality of the music, movies, or other content being played remains largely unchanged, while the sound remains clear and natural.
Disadvantages of feedforward ANC
- Feedforward ANC is less effective at canceling out low-frequency noise.
- Feedforward ANC relies on external microphones to pick up the ambient noise and generate anti-noise signals, which can be susceptible to wind noise or other environmental factors.
Feedback ANC
Feedback ANC is the exact opposite of feedforward ANC. In a feedback ANC system the microphone is positioned inside the ear cup or earphone housing to capture the sound that is present inside the headphones or earphones.
The captured sound may include the audio content, such as music or speech, as well as any external noises that have passed through the headphone or earphone drivers and reached the listener’s ears. Feedback ANC is often an effective method for reducing the impact of external noises on the listener’s ears while providing a more immersive listening experience in noisy environments.
Advantages of Feedback ANC
- Ideal for reducing low-frequency noise, such as the rumble of engines or the hum of air conditioners.
- Internal microphones are less susceptible to environmental factors such as wind noise and can provide more reliable performance in multiple listening environments.
- By using well-designed ear cups and materials that provide good passive noise isolation, feedback ANC can still provide some level of noise reduction even when the ANC circuit is not activated. This makes feedback ANC headphones a versatile option for different listening scenarios.
Disadvantages of Feedback ANC
- Tends to have higher latency compared to feedforward ANC
- Feedback ANC may result in slight changes to the audio quality, such as a reduction in bass response or overall audio volume. However, modern feedback ANC headphones are designed to minimize these effects and provide high-quality audio performance.
- Feedback ANC may have limitations in blocking sudden, impulsive noises or noises that are very close to the ear.
What is Hybrid ANC?
Hybrid ANC is an advanced form of Active Noise Cancellation that combines both feedforward and feedback ANC techniques to allow users to enjoy the best of both worlds. Hybrid ANC utilizes multiple microphones placed both outside and inside the ear cup or earphone housing to capture external noises as well as the sound inside the headphones or earphones.
The captured sound is then processed by the ANC circuit to generate anti-noise sound waves that are fed back into the system to cancel out both external noises and internal sounds. This takes advantage of the strengths of both feedforward and feedback ANC techniques to deliver the best listening experience.
Ideally, the feedforward microphones capture incoming noises from the environment, while the feedback microphones capture the sound that may be present inside the headphones or earphones. By combining the information from both types of microphones, the Hybrid ANC system can accurately detect and cancel out a wider range of noises, including both low-frequency and high-frequency noises, resulting in improved noise reduction.
One of the key advantages of Hybrid ANC is its ability to adapt to different noise environments and optimize the noise cancellation performance accordingly. The ANC system can also dynamically adjust the anti-noise sound waves based on the input from both the feedforward and feedback microphones, allowing for real-time adaptation to changing noise conditions.
This makes Hybrid ANC particularly effective in environments with varying noise levels or different types of noises. Hybrid ANC has also become increasingly popular in high-end headphones and earphones, as it offers advanced noise cancellation performance and improved listening experience.
It’s important to note that Hybrid ANC is not a magic solution, and it may not eliminate all external noise completely. Some noises, such as sudden loud noises or high-pitched sounds, may still be audible even with Hybrid ANC-enabled headphones.
Advantages of Hybrid ANC
- Improved noise cancellation performance- Hybrid ANC combines both feedforward and feedback ANC techniques, allowing for improved noise reduction performance compared to traditional feedforward or feedback ANC alone.
- Adaptive and dynamic noise cancellation- Hybrid ANC has the ability to adapt to different noise environments in real time by utilizing input from both feedforward and feedback microphones. This allows the ANC system to optimize the anti-noise sound waves for changing noise conditions, making it highly effective in any listening environment.
- Improved audio quality- Hybrid ANC can help to enhance audio quality by reducing the impact of external noises on the audio content. By canceling out external noises, it allows the listener to hear the audio content more clearly and with better clarity, especially in noisy environments
Disadvantages of Hybrid ANC
- Increased complexity and cost- Hybrid ANC systems typically require multiple microphones and more complex electronics to process the input from both feedforward and feedback microphones. This can increase the complexity and cost of the ANC system.
- Reduced battery life- The increased complexity of Hybrid ANC may require additional power consumption, which could potentially impact the battery life of the headphones or earphones. Depending on the specific implementation, the battery life of the device may be shorter compared to devices with simpler ANC systems.
- Design and form factor limitations- The additional microphones and electronics required for Hybrid ANC may impact the design and form factor of the headphones or earphones. These headphones may require larger or differently positioned microphones, which could affect the aesthetics, comfort, or portability of the device.
Conclusion
Hybrid ANC is often an effective way of reducing external noise and providing a high-quality listening experience. By combining multiple approaches, this technology is designed to block unwanted frequencies and intensities of noise, while offering improved performance in various environments.
However, its effectiveness can vary depending on the specific implementation in a particular set of headphones. Furthermore, factors such as the quality of microphones, the algorithms used for noise cancellation, and the design and fit of the headphones can all impact the performance of hybrid ANC headphones.
